1. Field of the Invention
The present invention relates to weld blankets that provide protection against weld spatter to auto body shop equipment, automobiles, and other industrial equipment. In particular, the present weld blanket is a non-woven, needle punched fabric comprising a plurality of precursor carbon fibers that have not been oxidized to a pure carbon fiber state, and which are tightly needle punched to an optimum density and weight to prohibit the burn-through of weld spatter.
2. Description of the Related Art
Ordinary welding blankets are either heavy and cumbersome or ineffective in stopping spatter burn-through. Technicians often choose not to use them because of this, resulting in damage from molten weld spatter on, for example, an automotive interior. A typical welding blanket may comprise unexpanded vermiculite and inorganic heat resistant fibrous material. See U.S. Pat. No. 4,849,273 to Skinner et al. Other known welding blankets have been made of various materials including vinyl, silica, glass fibers, Nomex® (aramid fiber)/Kevlar® (aramid fiber) fabric or “aramid fiber”. All such blankets are relatively expensive and may still be subject to a weld spatter burn-through. These blankets are not considered reliable where weld spatter can cause damage to expensive car interior fabrics relative to seating and carpeting, headliners, and anywhere else where the threat of this burn-through exists due to close proximity welding.
Recently, carbon fibers have been used for their respective heat resistant end uses. Different categories of carbon fibers are based on modulus, tensile strength, raw material and final heat treatment temperature. Carbon fiber has been the basis for carbon fiber hard parts for use in exotic, lightweight, yet strong automotive and motorcycle components. These components, as a result of carbon fiber use, are very expensive. Some are rigid and brittle and used in other composites; others are soft and supple and used in apparel. In U.S. Pat. No. 5,582,912, the carbonaceous fibers are crimped to be non-linear.
Fibers that ultimately make up the carbon-based products, called precursor fibers are made by pyrolytic carbonization of a modified acrylic fiber. They are partially carbonized fibers, which transform into carbon or graphite when they undergo further carbonization in an inert atmosphere at high temperature. They are often blended 50-50 with para-aramid fibers creating a heavy woven fabric that does not normally lend itself to weld blanket applications.
In addition to mechanical improvements in yarn and fabric manufacture, there have been rapid advances in processes that improve textile characteristics for industrial applications. The many types of modern textile fabrics, produced from both traditional and man-made materials, are often classified according to structure. One process, known as needlefelting, mechanically moves fibers into the Z-direction to ensure strength. Needlefelts can vary in fiber location, strength, density, weight, thickness, and fiber type. Distinctive “carding” allows the fibers to be needle punched together into a given weight, while densification occurs via the needle punching process.
It would be preferred then that blankets used for industrial applications be lightweight, inexpensive, and manageable, while at the same time be capable of prohibiting the burn-through of weld spatter, and providing other advantages over the current state of the art Thus, there is a need for a weld blanket to have the lightweight and heat resistant properties exhibited by carbon fibers, but at the same time be inexpensive, capable of being unblended, and still have the tensile strength and density required for absorbing molten metal.